Tractor equipped with a fifth wheel

ABSTRACT

The present invention relates to a tractor for transferring a variety of trailers and transfer devices (12) equipped with a kingpin (13), which tractor is equipped with a vertically adjustable 5th wheel (4). The 5th wheel (4) comprises gripping members (14, 15) and power mechanisms (16) by means of which the transfer device (12) is by the kingpin (13) with a convenient force pulled into contact with the 5th wheel 4 thus making an inner force balance of the joint 4-12 possible.

BACKGROUND OF THE INVENTION

The invention relates to a tractor for trailers and devices equippedwith a kingpin, used for transferring these in harbours, lorryterminals, industrial plants and elsewhere.

With the development of container transports the need to handle variouskinds of trailers, transfer devices and the like has grown substantiallyat points of departure and destinations and junctions in the traffic.Examples of this include the loading and unloading of semitrailers inroll on-roll off vessels (ro-ro vessels); transfers of semitrailers inlorry terminals, as well as e.g. transfers of swap bodies from points ofloading and unloading to stations where transport vehicles are waiting.

Traditionally these operations and transfers are carried out by means ofso-called terminal tractors which are two-axle vehicles similar tolorries. These vehicles are expensive and of complicated build, andowing to their great length, less maneuverable. Especially in freightstations and industry's internal transports old tractors removed fromactual road traffic have been reconditioned for short-range transfers.The only advantage of these vehicles lies in their relatively low price,in all other aspects they are inferior to the above mentioned terminaltractors.

Patent specification FI 50596 presents the principle of a single-axletractor equipped with a gooseneck. The vehicle is not directlyapplicable to the use described here. Patent specification CH 533570presents a transfer device with a 5th wheel for a semitrailer whichtransfer device grips the trailer by the kingpin. The device, however,is constructed in such a manner that in practice it is unable to controlforces directed to it from the trailer to be transferred, for exampleforces directed to it upon braking seek to rotate it around the kingpin.The clearances of an ordinary 5th wheel locking and the dynamic shocksthey enable damage either the pulling device or the kingpin upon suddenstress and make the transport a risky measure.

SUMMARY OF THE INVENTION

The above drawbacks can be decisively remedied by means of a tractoraccording to the invention. To achieve this the tractor according to theinvention is characterized in that the 5th wheel comprises grippingmeans and power mechanisms by means of which the device being coupled tothe 5th wheel is pressed by its kingpin into contact with the 5th wheel.

The creation of a practical and safe-to-use coupling between amaneuverable, single-axle tractor with low manufacturing costs and awheeled unit to be transferred can be regarded as the greatest advantageof the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention is described in detail with reference tothe enclosed drawing.

FIG. 1 is a side view of a tractor in accordance with the inventionequipped with a transfer device

FIG. 2 illustrates the same device as FIG. 1 but with the 5th wheel ofthe tractor in accordance with the invention in its raised position.

FIG. 3 illustrates a tractor in accordance with the invention seen fromabove.

FIG. 4 illustrates a section taken on the line I--I of FIG. 3

FIG. 5 is a cross-sectional view of the 5th wheel of a tractor inaccordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

A tractor 1 in accordance with the present invention comprises an axle 2shown in FIGS. 3 and 4 and thereto coupled wheels 3 equipped withhydraulic motors, a 5th wheel 4 coupled to axle 2 in a known mannerthrough a cylinder 6 and possibly a bearing 5, an auxiliary wheel 9coupled to a supporting structure 10 through cylinder 11, an enginespace 8, and a driver's cab 7. The cylinder 6 is fixed to the axle 2 insuch a manner that it cannot rotate around the axle 2. The engine space8 accommodates the motor, a hydraulic pump, tanks and other devices andthe driver's cab 7 accommodates the controls of the tractor 1, a benchetc. While the tractor is not coupled into a trailer to be transportedor similar, the auxiliary wheel 9 is by means of the cylinder 11 pressedto a supporting position shown in FIG. 4 for the transfer of the tractor1 in an unloaded state. The auxiliary wheel 9 is of a so-called freerotating type seeking its direction according to the direction where thetractor 1 moves. The 5th wheel 4 may be equipped with the bearing 5 atthe point where it is connected to the cylinder 6.

In FIG. 1 a known transfer device 12 has been attached to the tractor 1through the 5th wheel 4. The transport device 12 is in a loweredposition. By adjusting the cylinder 6 conveniently the transport device12 can be lifted as shown in FIG. 2. The transfer device 12 may be e.g.a lifting wagon for the handling of platforms with legs or it may be asemitrailer or some other device equipped with a known standardizedkingpin 13. By regulating the hydraulic motors of the wheels 3conveniently it is possible to make the tractor 1 turn in relation tothe kingpin 13 and thus steer the combination of the tractor and thetransfer device 1-12.

FIG. 5 illustrates a cross-sectional view of the coupling of the tractor1 and the transfer device 12 shown in FIGS. 1 and 2. The 5th wheel 4comprises a known aperture 17 or similar, through which the kingpin 13is guidely directed into the space inside the 5th wheel where there is afork 14 operated by cylinders 15 and 16. Cylinders 15 and 16 arearranged to move the fork in a horizontal direction and verticaldirection, respectively, so that the loop of the fork 14 is capable ofgripping the kingpin 13. The fork 14 is used to grip the kingpin 13 in aknown manner. The kingpin 13 is by means of the cylinder 16 pressed intocontact with the 5th wheel 4. By choosing the force of the cylinder 16appropriately it is possible to eliminate a substantial part of theforces directed towards the kingpin coupling in a driving situation. Ifthe pulling force of the cylinder 16 is chosen to be equal to the forcewith which the transfer device 12 bears against the 5th wheel 4, allinner forces produced by acceleration or braking at the coupling pointwill theoretically be eliminated. The 5th wheel 4 may be equipped withsuch known sensors by means of which a force concerned at any given timecan be determined, and on the basis of this information the force of thecylinder 16 is adjusted to a desired level by means of known devices andmethods. The pressing of the 5th wheel 4 against the surroundings of thekingpin 13 of the transfer device 12 upon pulling by means of thecylinder 16 by the kingpin 13 will substantially increase friction atthe connecting point. To ensure a smooth turning the joint between the5th wheel 4 and cylinder 6 may be equipped with a bearing 5 havingconsiderably greater dimensions than a conventional 5th wheel andkingpin combination and thus a better transmission capacity.

It is possible to grip the kingpin 13 in many other ways, too, and notonly by means of a fork but also by such known ways of gripping in whichthe total gripping area of the kingpin 13 is utilized. In addition tothe method of pulling directly by means of the cylinder 16 the forceacting on the kingpin 13 may also be produced by using different leverand other mechanisms. The 5th wheel 4 may, in addition to the bearing 5,also be equipped with a known spring that always turns an unstressed 5thwheel 4 to the position shown in FIG. 3. On the other hand, the 5thwheel 4 may also be of such construction that the kingpin 13 is coupledsubstantially in vertical direction and not so much guidedly on laterallevel as conventionally. In this case the upper surface of the 5th wheel4 is rather a level disc having an aperture fit for the kingpin 13 andpossibly slightly conic guiding surfaces in the center.

In any case it is to be understood that the invention has above beendescribed with reference to a few preferred embodiments only, however,not wanting to restrict the applications of the invention to theseembodiments only, several modifications being possible within the scopeof the inventive idea as defined by the following claims.

I claim:
 1. A tractor equipped with a 5th wheel for couplingsemitrailers and devices to be transferred equipped with a kingpincoupling, comprising:a tractor equipped with a power source withcontrols, a vertically adjustable 5th wheel arranged in said tractor,said 5th wheel comprising gripping means for gripping the kingpin of thedevice being coupled, movement means for moving said gripping means in ahorizontal direction, power mechanisms for moving said gripping means ina vertical direction to thereby press the kingpin of the device beingcoupled into contact with said 5th wheel.
 2. The tractor of claim 1,further comprising a bearing and adjusting means for verticallyadjusting said 5th wheel, said adjusting means being connected to said5th wheel through said bearing.
 3. The tractor of claim 1, wherein saidgripping means comprise a movable gripping member arrangedperpendicularly to an axial direction of the kingpin of the device beingcoupled.
 4. The tractor of claim 1, further comprising an axle havingwheels attached thereto, and wherein said gripping means comprise amovable fork arranged substantially in a direction of said axle.
 5. Thetractor of claim 2, wherein said adjusting means adjust said 5th wheeltoward and away from the device being transferred.
 6. The tractor ofclaim 3, wherein said gripping member comprise a fork.
 7. The tractor ofclaim 4, wherein said movable fork has an aperture into which thekingpin of the coupled device is directed.
 8. The tractor of claim 4,wherein said movement means comprise a first cylinder connected to saidfork, said first cylinder directing said fork in the horizontaldirection to grip the kingpin of the coupled device.
 9. The tractor ofclaim 8, wherein said power mechanisms comprise a second cylinder fordirecting said fork in the vertical direction.
 10. The tractor of claim9, wherein said second cylinder directs the kingpin in a verticaldirection into contact with said 5th wheel.
 11. The tractor of claim 9,wherein said second cylinder applies a force to said fork after thekingpin is coupled to said 5th wheel such that forces directed to thekingpin when said tractor is moving are substantially eliminated. 12.The tractor of claim 9, wherein said second cylinder applies a force tosaid fork after the kingpin is coupled to said 5th wheel such that theforce applied by said second cylinder is substantially equal to a forceof the coupled device against said 5th wheel.
 13. The tractor of claim1, wherein said 5th wheel comprises a level disc having an aperturethrough which the kingpin of the device being coupled is arranged toenter, said level disc having slight conic guiding surfaces in a centralarea.
 14. A tractor equipped with a 5th wheel for coupling andtransferring semitrailers and devices equipped with kingpin couplings,comprising:a vertically adjustable 5th wheel coupled to an axle of thetractor through a first adjustable cylinder, gripping means for grippingthe kingpin coupling of the device being coupled when the kingpin ispassed through an aperture in said 5th wheel, movement means for movingsaid gripping means in a horizontal direction, and power mechanismsconnected to said gripping means for moving said gripping means in avertical direction to thereby direct said gripping means into contactwith the 5th wheel.
 15. The tractor of claim 14, wherein said grippingmeans comprise a fork, said power mechanisms comprise a secondadjustable cylinder arranged to direct said fork in the verticaldirection and said movement means comprise a third adjustable cylinderarranged to direct said fork in the horizontal direction.